How many possible FreeCell deals are there?

1 Answer

Strictly speaking there are 52! different deals, about 8×10^67. However, deals can be transformed in several ways which make no mathematical difference, which cuts down the number a bit. The four left-hand (7 card) columns can be interchanged in 4! (24) ways, as can the four right-hand (6 card) columns. Also, suits can be interchanged in certain ways. If you swap suits so that all the black cards become red and vice versa (there are 4 ways to do this: SHCD can become HCDS, HSDC, DCHS, or DSHC respectively), the mathematical properties of the deal do not change; you can also maintain colors, but swap spades for clubs, diamonds for hearts, or both (3 more ways). So there are 576 permutations of columns (including no swaps) and 8 permutations of suits (including no swaps), which reduces the number of essentially different FreeCell deals to roughly 1.75×10^64 (a few rare deals will be identical under one of the 4608 transformations). The 32-bit integers used in FreeCell Pro and other progr